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EP 1 204 503 B1 |
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EUROPEAN PATENT SPECIFICATION |
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Mention of the grant of the patent: |
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13.10.2004 Bulletin 2004/42 |
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Date of filing: 13.06.2000 |
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International application number: |
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PCT/SE2000/001236 |
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International publication number: |
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WO 2000/078489 (28.12.2000 Gazette 2000/52) |
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DEEP HOLE DRILL
TIEFLOCHBOHRER
FORET POUR TROU PROFOND
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Designated Contracting States: |
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AT DE FR GB IT SE |
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Priority: |
21.06.1999 SE 9902354
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Date of publication of application: |
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15.05.2002 Bulletin 2002/20 |
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Proprietor: SANDVIK AKTIEBOLAG |
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811 81 Sandviken (SE) |
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Inventors: |
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- LINDBLOM, Stefan
S-804 27 Gävle (SE)
- DANIELSSON, Ake
S-811 33 Sandviken (SE)
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(56) |
References cited: :
WO-A1-95/34397 US-A- 2 912 887
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US-A- 1 304 981
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Note: Within nine months from the publication of the mention of the grant of the European
patent, any person may give notice to the European Patent Office of opposition to
the European patent
granted. Notice of opposition shall be filed in a written reasoned statement. It shall
not be deemed to
have been filed until the opposition fee has been paid. (Art. 99(1) European Patent
Convention).
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[0001] The present invention relates to a deep hole drill, which comprises a cutter head
as well as a connecting part integrated with the cutter head which part has a thread,
said cutter head being equipped with a chip removing cutting insert, at least one
support pad as well as at least one guide bar, the said cutter head has at least one
opening for discharging chips, said opening transforming into an inner channel of
the cutter head. Such a deep hole drill is, according to the preamble of claim 1,
e.g. known from WO 95/34397 A. The two most common systems in deep hole drilling are
presently the STS (Single Tube System) system and the Ejector system. the present
invention relates to both these systems.
Prior art
[0002] In deep hole drilling, a commonly occurring problem is that the support pads and
guide bars, which are arranged on the cutter head, are subjected to the formation
of crack, during the deep hole drilling. The reason for this is that the support pads/guide
bars are normally made of solid cemented carbide, whereby said support pads/guide
bars may be exchangeably fixed on the cutter head or in various ways connected by
soldering to the cutter head. During the drilling process, the support pads/guide
bars are exposed to high temperatures by the fact that the friction against the hole
wall may be high. However, it is most often so that the entire support pad/guide bar
does not abut against the hole wall, and therefore only a part of said support pad/guide
bar is exposed to said friction. The cooling liquid flowing between the cutter head
and the bore hole will not be in contact with the support pad/guide bar in those areas
where abutment takes place between the support pad/guide bar and the hole wall to
a sufficient extent. As a consequence of these interacting circumstances, i.e. high
friction and deficient cooling, cracks arise in the support pads/guide bars, which
reduce the service life of said support pads/guide bars.
Aims and features of the invention
[0003] The present invention has as its aim the definition of a deep hole drill of the kind
mentioned in the introduction, where the cooling liquid is given a greater possibility
to provide cooling of the support pad/guide bar, in an efficient way, during drilling.
[0004] Yet another aim of the invention is to improve the chip removal, which reduces the
risk for chips being stuck between the support pad/guide bar and the hole wall, which
additionally may reduce the service life of said support pads/guide bars.
[0005] The aims of the present invention are realised by means of a deep hole drill having
the features mentioned in the subsequent claims. Preferred embodiments of the invention
are defined in the dependent claims.
Brief description of the drawings
[0006] Below an embodiment of the invention will be described, reference being made to the
accompanying drawings, where
- Fig 1
- shows a front view of a deep hole drill according to prior art;
- Fig 2
- shows a front view of an embodiment of a deep hole drill according to the present
invention;
- Fig 3
- shows a perspective view obliquely from below of the deep hole drill according to
Fig 2;
- Fig 4
- shows a perspective view obliquely from above of the deep hole drill according to
Fig 2;
- Fig 5
- shows a front view of the deep hole drill according to Fig 2, where the resultant
of the cutting forces as well as the forces acting on the support pad and the guide
bars are indicated;
- Fig 6
- shows schematically the surface, which lets through cooling liquid on a deep hole
drill according to prior art;
- Fig 7
- shows schematically the surface which lets through cooling liquid on a deep hole drill
according to the present invention; and
- Fig 8
- shows a perspective view of an alternative embodiment of a deep hole drill according
to the present invention.
Description of prior art as well as a first embodiment of a deep hole drill according
to the present invention
[0007] The deep hole drill A according to the prior art illustrated in fig 1 is provided
with a support pad B and a guide bar C. In that connection, no special arrangements
are taken to overcome the problems which have been discussed above under the heading
Prior art, i.e. that the support pad B and the guide bar C are subject to crack formation.
[0008] The deep hole drill according to the present invention illustrated in figs 2-5 comprises
a cutter head 1 as well as a connecting part 3 integrated with the cutter head 1,
which connecting part is provided with an external thread 5. The connecting part 3
is connected to a drill tube (not shown), via said external thread 5, which in turn
is carried by a suitable supporting device.
[0009] The cutter head 1 is, in the usual way, equipped with cutting inserts 7, these however
not being described in detail since they do not constitute a part of the present invention.
Furthermore, the cutter head 1 is provided with a support pad 9 and a guide bar 10,
which in the embodiment illustrated consist of exchangeable units according to the
principle of indexable inserts. As is most clearly seen in Fig 3, the support pad
9 and the guide bar 10 are provided with a chamfers 11 and 12, respectively, at the
end thereof turned towards the connecting part 3. In that connection, the chamfers
11, 12 are so formed that their abutment against the cutter head 1 takes place without
there being any difference in level between the chamfers 11, 12 and the portions of
the cutter head 1 which said chamfers 11, 12 abut against.
[0010] The cutter head 1 of the deep hole drill according to the present invention is also
provided with a first cooling duct 13 and a second cooling duct 14, the first cooling
duct 13 being situated adjacent to the support pad 9 while the second cooling duct
14 being situated adjacent to the guide bar 10. Said cooling ducts 13, 14 extend in
the axial direction of the deep hole drill and are preferably parallel to the axial
direction of the deep hole drill. In the embodiment illustrated, the cooling ducts
13, 14 are formed as concave countersinks in the cutter head 1, the cooling ducts
having, when seen in cross-section, a softly rounded bottom with a certain radius
of curvature.
[0011] The cutter head 1 is provided, in the usual way, with an inner channel for discharging
the chips produced during the rotation of the cutter head 1 in relation to the workpiece.
In that connection, the cutter head 1 is provided with a first opening 15, through
which the majority of the chips produced are discharged, said first opening 15 being
connected to the interior channel of the cutter head 1. The cutter head 1 has also
a second opening 16, which also is used to discharge chips, said second opening 16
also being in connection with the interior channel. In the illustrated embodiment,
the first opening 15 is somewhat larger than the second opening 16.
The function of the deep hole drill according to the invention
[0012] In conjunction with a hole being drilled in a work-piece, this is clamped in a kind
of fixture while the deep hole drill with the drill tube thereof is clamped in a rotatable
chuck, and then the workpiece and the deep hole drill are pressed up against each
other. The deep hole drill with the drill tube thereof is then brought to rotate and
is displaced axially in relation to the workpiece, a hole being drilled in said workpiece.
During the drilling process, the support pad 9 and the guide bar 10 abut against the
hole wall, whereby a temperature rise takes place in the support pad 9 and the guide
bar 10 by virtue of the friction against the hole wall. In this connection, reference
is made to fig 5 which, on one hand, shows the resultant R of the radial cutting forces
exerted by the cutting inserts 7 and, on the other hand, the forces acting from the
hole wall on the support pad 9 and the guide bar 10 which compensate said resultant
R. Then, it should be noted that force F1 acting on the support pad 9 is larger than
the force F2 acting on the guide bar 10. As a result of this force distribution, the
support pad 9 is exposed to a larger friction and thereby also a greater temperature
rise.
[0013] In order to compensate for said temperature rise, cooling medium, commonly oil, is
supplied into the space between the drill tube of the deep hole drill and the hole
wall when an STS system is concerned, said cooling medium being brought to flow in
the direction towards the cutter head 1. When the cooling medium reaches the cutter
head 1, an accumulation of cooling medium takes place in the first and second cooling
duct 13 and 14, respectively, the main part of the cooling medium flowing to the free
chip removing end of the cutter head 1 via the first and second cooling ducts 13 and
14, respectively. Since the cutter head 1 rotates in the direction of the arrow S,
see fig 5, i.e. the support pad 9 is to be found behind the first cooling duct 13
in the direction of rotation, said support pad 9 will pass through the accumulation
of cooling medium which is generated by the first cooling duct 13. Thereby, a significantly
improved cooling of the support pad 9 is achieved in comparison with the cooling which
is obtained for a deep hole drill according to prior art.
[0014] It is true that a corresponding cooling of the guide bar 10 is not obtained, but
an equally satisfactory cooling of the guide bar 10 is not required since the same
it is exposed to a force F2 from the hole wall which is significantly smaller than
the force F1 which the support pad 9 is exposed to.
[0015] In figs 6 and 7, the difference in volume of cooling medium reaching the chip removing
end of the cutter head 1 is schematically illustrated for a deep hole drill according
to prior art, fig 6, and for a deep hole drill according to the present invention,
fig 7. The dashed surfaces in figs 6 and 7 represent the surfaces that are available
for the cooling medium to flow forward in. For a deep hole drill according to prior
art, see fig 6, the available surface is approx. 12 % of the cross-section area of
the drilled hole, while for a deep hole drill according to the present invention,
see fig 7, the available surface for the cooling medium is approx. 15 %. This equals
an increase of approx. 20 % when comparing deep hole drill according to prior art
and a deep hole drill according to the present invention.
[0016] The increased volume of cooling medium which reaches the chip removing end of the
cutter head 1 is, naturally, positive for the chip removal since the cooling medium
turns at the chip removing end and pulls the chips with it through the first opening
15 and the second opening 16. The fact that the second cooling duct 14 is situated
quite in front of the first opening 15, seen in the direction of rotation S, see fig
5, of the cutter head 1, ensures that an accumulated volume of cooling medium can
turn back and flow through the first opening 15, said accumulated volume of cooling
medium in an efficient way pulling chips with it from the chip removing end of the
cutter head 1. The cooling medium then continues in the interior channel of the deep
hole drill and further inside in the appurtenant drill tube (not shown).
Alternative embodiment of a deep hole drill according to the present invention
[0017] The deep hole drill illustrated in fig 8 comprises, like the embodiment according
to figs 3-5, a cutter head 1' as well as a fastening part 3, which in principle is
identical with the fastening part 3 of the embodiment illustrated in figs 3-5. The
design of the cutter head 1' is what distinguishes the deep hole drill according to
fig 8 from the deep hole drill according to figs 3-5, and more precisely the arrangement
of an additional cooling duct 17', i.e. a third cooling duct, which is situated besides
and quite close to the guide bar 10. Thus, the deep hole drill according to fig 8
is provided with a first and a second cooling medium duct 13 and 14, respectively,
which is seen in fig 8. If the same direction of rotation is valid for the deep hole
drill according to fig 8 as the deep hole drill according to figs 3-5, see arrow S
in fig 5, the third cooling duct 17' is positioned in front of the guide bar 10 in
said direction of rotation S. Said third cooling duct 17' should guarantee that the
guide bar 10 receives a satisfactory cooling/lubrication by the cooling medium flowing
in the third cooling duct 17'. Normally, the third cooling duct 17' has smaller dimensions
than the first and second cooling ducts 13 and 14.
Feasible modifications of the invention
[0018] In the embodiment described above, two cooling ducts 13, 14 are arranged on the circumference
of the cutter head 1. However, within the scope of the invention, it is feasible that
only one cooling duct is arranged on the circumference of the cutter head 1, the cooling
duct 13 which is arranged adjacent to the support pad 9, in that case, being preferable.
The reason for this is seen in the description above when the cooling of the support
pad 9 is discussed.
[0019] In the embodiment described above, the two cooling ducts 13, 14 are shown having
in the main the same flow cross-section in fig 2. However, within the scope of the
present invention, it is conceivable that, for instance, the second cooling duct 14
has a larger flow cross-section than the first cooling duct 13 since said second cooling
duct 14 should serve two cutting inserts, i.e. let cooling medium pass which discharges
chips from two cutting inserts.
[0020] In the embodiment described above, the support pad 7 and the guide bar 9 are in the
form of exchangeable units according to the principle of indexable inserts. However,
within the scope of the invention, it is feasible that the support pad/guide bar is
connected by soldering to the cutter head 1 of the deep hole drill.
[0021] In the description above of the function of the deep hole drill according to the
invention, it has been assumed that the so-called STS system is used. However, a deep
hole drill according to the present invention may also be used, which has been pointed
out in the introduction of this patent application, in, for instance, the so called
Ejector system or other existing systems for deep hole drilling. In the Ejector system,
double drill tubes are used, approximately half of the cooling medium turning around
before it reaches the chip removing end of the cutter head I and thereby providing
an Ejector effect which activates the cooling medium reaching the chip removing end
and transports chips with it on its way from the chip removing end.
[0022] In the above description of the function of the deep hole drill according to the
invention, the deep hole drill is rotated while the workpiece is not rotated. However,
it is also feasible, within the scope of the invention as defined by the appended
claims, that the workpiece rotates while the deep hole drill do not rotate but only
is axially displaced in relation to the workpiece. According to an additional variant,
it is conceivable that both the deep hole drill and the workpiece rotate in opposite
directions.
[0023] Reference being made to fig 7, it should be pointed out that the dashed cross-section
surface besides the cooling ducts, being concave in cross-section, may, within the
scope of the invention as defined by the appended claims, be blocked for cooling medium,
at which said blocking member may consist of fibre strips or the like, applied on
the outside of the cutter head. By such an arrangement, the cooling medium is forced
to flow only in said cooling ducts, at which an additionally improved cooling of the
support pad/guide bar may be counted upon.
1. Deep hole drill, which comprises a cutter head (1; 1') as well as a connecting part
(3) integrated with the cutter head (1; 1'), which part is intended to be connected
to a drill tube, said cutter head (1; 1') being equipped with a chip removing cutting
insert (7), at least one support pad (9) as well as at least one guide bar (10), that
said cutter head (1) has at least one opening (15, 16) for discharging chips, said
opening (15, 16) transforming into an inner channel of the cutter head (1; 1'), characterized in, that at least one cooling duct (13) is arranged on the circumference of the cutter head
(1; 1'), which cooling duct extends in the axial direction of the deep hole drill,
and that the cooling duct (13) is arranged adjacent to the support pad (9).
2. Deep hole drill according to claim 1, characterized in, that the cooling duct (13) is arranged in front of the support pad (9), seen in the direction
of rotation of the deep hole drill, or behind the support pad (9), seen in the direction
of rotation of the workpiece in case the deep hole drill does not rotate.
3. Deep hole drill according to one of the preceding claims, characterized in, that two cooling ducts (13, 14) are arranged on the circumference of the cutter head (1),
and that the second cooling duct (14) also extends in the axial direction of the deep
hole drill.
4. Deep hole drill according to claim 3, characterized in, that the second cooling duct (14) is arranged adjacent to the guide bar (10).
5. Deep hole drill according to claim 4, characterized in, that the second cooling duct (14) is arranged behind the guide bar (10), seen in the direction
of rotation of the deep hole drill, or in front of the guide bar (10), seen in the
direction of rotation of the workpiece in case the deep hole drill does not rotate.
6. Deep hole drill according to one of the preceding claims 4-5, characterized in, that the second cooling duct (14) has a larger flow cross-section than the first cooling
duct (13).
7. Deep hole drill according to one of the preceding claims, characterized in, that the cooling duct (13) the cooling ducts (13, 14) consist/consists of concave countersinks
having a softly rounded bottom with a certain radius of curvature.
8. Deep hole drill according to one of the preceding claims, characterized in, that the cutter head (1') is provided with a cooling duct (17') in direct proximity to
the guide bar (10).
9. Deep hole drill according to claim 8, characterized in, that said cooling duct (17') is arranged in front of the guide bar (10), seen in the direction
of rotation of the deep hole drill, or behind the guide bar (10), seen in the direction
of rotation of the workpiece in case the deep hole drill does not rotate.
1. Tieflochbohrer, welcher einen Schneidkopf (1; 1') als auch einen Verbindungsteil (3),
der integrierender Bestandteil des Schneidkopfes (1; 1') ist, umfaßt, wobei dieser
Teil an eine Bohrerröhre angeschlossen werden soll, wobei der Schneidkopf (1; 1')
mit einem spanabhebenden Einsatz (7), wenigstens einer Stützunterlage (9) als auch
wenigstens einem Führungsstab (10) ausgestattet ist, wobei der Schneidkopf (1) wenigstens
eine Öffnung (15, 16) für die Entfernung von Spänen hat und wobei die Öffnung (15,
16) in einen inneren Kanal des Schneidkopfes (1; 1') übergeht, dadurch gekennzeichnet, daß wenigstens eine Kühlleitung (13) an dem Umfang des Schneidkopfes (1; 1') angeordnet
ist, wobei sich die Kühlleitung in der axialen Richtung des Tieflochbohrers erstreckt,
und daß die Kühlleitung (13) nahe an der Stützunterlage (9) angeordnet ist.
2. Tieflochbohrer nach Anspruch 1, dadurch gekennzeichnet, daß die Kühlleitung (13), in der Drehrichtung des Tieflochbohrers betrachtet, vor der
Stützunterlage (9), oder, für den Fall, daß der Tieflochbohrer sich nicht dreht, in
der Drehrichtung des Werkstücks betrachtet, hinter der Stützunterlage (9) angeordnet
ist.
3. Tieflochbohrer nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß zwei Kühlleitungen (13, 14) an dem Umfang des Schneidkopfes (1; 1') angeordnet sind,
und daß die zweite Kühlleitung (14) sich ebenfalls in der axialen Richtung des Tieflochbohrers
erstreckt.
4. Tieflochbohrer nach Anspruch 3, dadurch gekennzeichnet, daß die zweite Kühlleitung (14) in der Nähe des Führungsstabs (10) angeordnet ist.
5. Tieflochbohrer nach Anspruch 4, dadurch gekennzeichnet, daß die zweite Kühlleitung (14), in der Drehrichtung des Tieflochbohrers betrachtet,
hinter dem Führungsstab (10), oder, für den Fall, daß der Tieflochbohrer sich nicht
dreht, in der Drehrichtung des Werkstücks betrachtet, vor dem Führungsstab (10) angeordnet
ist.
6. Tieflochbohrer nach einem der vorhergehenden Ansprüche 4-5, dadurch gekennzeichnet, daß die zweite Kühlleitung (14) einen größeren Fließquerschnitt hat als die erste Kühlleitung
(13).
7. Tieflochbohrer nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß die Kühlleitung (13)/die Kühlleitungen (13, 14) aus konkaven Spitzsenken mit einem
leicht abgerundeten Boden mit einem bestimmten Krümmungsradius besteht/bestehen.
8. Tieflochbohrer nach einem der vorhergehenden Ansprüche, dadurch gekennzeichnet, daß der Schneidkopf (1') mit einer Kühlleitung (17') in direkter nächster Nähe zu dem
Führungsstab (10) ausgestattet ist.
9. Tieflochbohrer nach Anspruch 8, dadurch gekennzeichnet, daß die Kühlleitung (17'), in der Drehrichtung des Tieflochbohrers betrachtet, vor dem
Führungsstab (10), oder, für den Fall, daß der Tieflochbohrer sich nicht dreht, in
der Drehrichtung des Werkstücks betrachtet, hinter dem Führungsstab (10) angeordnet
ist.
1. Foret pour trou profond, comprenant une tête de coupe (1 ; 1') ainsi qu'une partie
de connexion (3) intégrée dans la tête de coupe (1 ; 1'), cette partie étant prévue
pour être reliée à un tube de perçage, la tête de coupe (1 ; 1') étant équipée d'une
plaquette de coupe par enlèvement de copeaux (7), d'au moins un patin support (9)
ainsi qu'au moins une barre de guidage (10), la tête de coupe (1) ayant au moins une
ouverture (15, 16) d'évacuation de copeaux, l'ouverture (15, 16) se transformant en
un canal interne de la tête de coupe (1 ; 1'), caractérisé par le fait qu'au moins un conduit de refroidissement (13) est situé sur la circonférence de la tête
de coupe (1 ; 1'), ce conduit de refroidissement s'étendant dans la direction axiale
du foret pour trou profond, et que le conduit de refroidissement (13) est situé de
façon adjacente au patin support (9).
2. Foret pour trou profond selon la revendication 1, caractérisé par le fait que le conduit de refroidissement (13) est situé devant le patin support (9), en vue
dans la direction de rotation du foret pour trou profond, ou derrière le patin support
(9), en vue dans la direction de la pièce à usiner dans le cas où le foret pour trou
profond ne tourne pas.
3. Foret pour trou profond selon l'une des revendications précédentes, caractérisé par le fait que deux conduits de refroidissement (13, 14) sont situés sur la circonférence de la
tête de coupe (1), et que le second conduit de refroidissement (14) s'étend aussi
dans. la direction axiale du foret pour trou profond.
4. Foret pour trou profond selon la revendication 3, caractérisé par le fait que le second conduit de refroidissement (14) est situé de façon adjacente à la barre
de guidage (10).
5. Foret pour trou profond selon la revendication 4, caractérisé par le fait que le second conduit de refroidissement (14) est situé derrière la barre de guidage
(10), en vue dans la direction de rotation du foret pour trou profond, ou devant la
barre de guidage (10), en vue dans la direction de rotation de la pièce à usiner dans
le cas où le foret pour trou profond ne tourne pas.
6. Foret pour trou profond selon l'une des revendications précédentes 4 et 5, caractérisé par le fait que le second conduit de refroidissement (14) a une section transversale de passage plus
grande que le premier conduit de refroidissement (13).
7. Foret pour trou profond selon l'une des revendications précédentes, caractérisé par le fait que le ou les conduits de refroidissement (13 ; 13, 14) consistent en des fraisages concaves
ayant un fond doucement arrondi avec un certain rayon de courbure.
8. Foret pour trou profond selon l'une des revendications précédentes, caractérisé par le fait que la tête de coupe (1') comporte un conduit de refroidissement (17') à proximité directe
de la barre de guidage (10).
9. Foret pour trou profond selon la revendication 8, caractérisé par le fait que le conduit de refroidissement (17') est situé devant la barre de guidage (10), en
vue dans la direction de rotation du foret pour trou profond, ou derrière la barre
de guidage (10), en vue dans. la direction de rotation de la pièce à usiner dans le
cas où le foret pour trou profond ne tourne pas.